Apparatus for cleaning gramophone discs



Oct. 3, 1967 A. PHILLIPSON ETAL APPARATUS FOR CLEANING GRAMOPHONE DISCS 2 Sheets-Sheet 1 I Filed July 20, 1964 1967 A. PHlLLlPSON ETAL 3,345,075 ,7

APPARATUS FOR CLEANING GRAMOPHONE DISCS Filed July 20, 1964 2 sneets-sneet'z ummmm United States Patent 3,345,075 APPARATUS FOR CLEANING GRAMOPHONE DISCS Alan Phillipson, Basil Harry Royston Spiller, Robin Smith, and Harry Cheesrnan, all of London, England, assignors to Decca Limited, London, England, a British company Filed July 20, 1964, Ser. No. 383,839 Claims priority, application Great Britain, July 24, 1963, 29,381/ 63 7 Claims. (Cl. 274-47) ABSTRACT OF THE DISCLOSURE Apparatus for cleaning blank gramophone discs before their embossing with sound tracks. Each disc is freely supported for rotation in spaced vertical grooves down which it can slid to an operating position whereat it is supported by a withdrawable latch. Perforated tubes eX- tending across the faces of the disc direct gas jets thereon to cause the disc to rotate; the disc is cleaned of dust by the combined action of the jets and centrifugal force.

This invention relates to the manufacture of gramophone records. Gramophone records are easily damaged by dirt particles and it is essential that in all stages of their manufacture discs be kept clean.

According to one aspect of this invention there is pro-- vided a method of cleaning a gramophone record disc comprising supporting the disc for rotation substantially about its axis and directing jets of gas on to the disc to cause it to rotate so that dust particles are removed by the combined effect of centrifugal force and the gas jets. According to another aspect of this invention there is provided apparatus for cleaning a gramophone record disc comprising means for supporting the disc for rotation about its axis and means for directing jets of gas on to the disc to cause it to rotate so that dust particles are removed by the combined effect of centrifugal force and the gas jets.

When the manufacture of gramophone records is carried out in a number of stages, the records tend to accumulate dirt between the stages. One such multi-stage process is the manufacture of records by embossing a sound track on a pre-formed disc, that is to say a disc of the required size and shape but without any sound track..In such a process it is necessary to clean the disc before the sound track is embossed. The invention includes, in the manufacture of a gramophone record by embossing a sound track on a pro-formed disc, a method of cleaning the disc before embossing the sound track comprising supporting the disc for rotation substantially about its axis and directing jets of gas on to the disc to cause it to rotate so that dust particles are removed by the combined effect of centrifugal force and the gas jets.

The disc is preferably supported within a chamber which is at least substantially closed and wherein gas is extracted from the chamber. The gas is preferably air.

An example of the invention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a front elevation, partly cut away, of disc cleaning apparatus;

FIGURE 2 is a View on line 22 of FIGURE 1; and

FIGURE 3 is a side elevation, partly cut away to show a section, of a component of FIGURE 1.

The example of the invention is used in the manufacture of gramophone records by embossing the sound tracks on pre-formed discs 11. The discs 11 are formed, for example by injection moulding, with a central hole 12, an inner annulus 13 around the hole and an outer annulus 14 around the inner annulus on which outer annulus the sound track is to be embossed. The inner annulus 13 is thicker than the outer annulus so that when records are stacked the sound tracks of adjacent records are not in contact.

The embossing operation may be carried out at a higher speed than the disc forming operation. As the demand for gramophone records is not steady throughout the year, it is convenient to use a few machines to pre-form discs steadily throughout the year and to store the discs ready for embossing at high speed when required.

When a pre-formed disc is to be embossed, it is removed from store and cleaned so that no contamination is pressed into the disc by the embossing dies. The embossing dies are heated, and in order to prevent distortion of the disc when the outer annulus is heated in the dies While the inner annulus remains cool, the inner annulus is pre-heated immediately before the outer annulus is embossed.

After embossing, the record disc is labelled and packed. Conveniently the disc passes from one operation to another by rolling or sliding down chutes.

The cleaning operation is carried out in a substantially closed rectangular chamber 15. The top of the chamber is formed by a nylon plate 16 which has a narrow slit 17 by which a disc 11 may enter the chamber 15. The central portion of the slit 17 is widened to accommodate the thicker inner annulus 13. The bottom is formed by four brass guide strips 18 arranged in pairs, two strips on the front 19 of the chamber 15 and two on the back 21. A slit 22 is left between the guide strips 18, the sides of this lower slit being faced by nylon strips 23 attached to the brass strips 18. The lower slit 22 is located immediately below the slit 17 in the top side plate 16. Grooved nylon runners 24 guide the edges of the disc 11 between the two slits 17, 22. All sharp edges are chamfered to avoid scratching the disc.

A solenoid operated latch 25 is located near one end of the bottom side, the latch 25 normally protruding into the lower slit 22. One guide strip is cut away to receive the solenoid 26 of the latch 25. Between the pairs of guide strips is a lamp-and-photocell device, the lamp 27 being mounted on the rear 21 of the chamber, and the photocell (not shown) on the front 19. A transparent hinged access door 28 is formed in the front 19 of the chamber 15.

An air inlet manifold 31 is located at one side of the chamber 15 and two pipes 32 extend across the chamber 15 from the manifold 31, one pipe on either side of the position of the disc 11 when the disc is in the chamber resting on the latch 25. The pipes 32 are closed at their free ends 32 (see FIGURE 3), and the pipe walls are perforated near the free ends. The perforations 34 are directed at 45 to the upward vertical towards the outer annulus of the disc 11. The perforations nearer the rim of the disc are smaller than those nearer the central hole. In this particular arrangement there are fourteen equispaced perforations in each tube, nine being 0.031 inch in diameter and give being 0.040 inch in diameter. An air outlet 35 is formed in the side of the chamber opposite the inlet manifold 31, and the outlet 35 is connected to air extraction apparatus (not shown).

The disc 11 to be cleaned falls into the chamber 15 in a vertical plane through the top slit 17, and is retained on the latch 25. The lowest part of the disc 11 cuts off the light of the lamp 27 from the photocell, so that the presence of the disc 11 in position in the chamber 15 is registered. Dry clean air under pressure is supplied through the manifold 31 to the pipes 32 so that jets of air from the perforations 34 are directed upwards on both faces of the disc 11 on one side of the vertical centre line through the disc only. That side of the disc is thus forced 3 upwards and the disc rotates substantially about its axis. The disc 11 is stabilised by the top plate 16, the side nylon runners 24 and the nylon guide strip faces 23.

Particles of dirt on the disc 11 are removed partly by the action of the air jets on the disc and partly by the centrifugal action of the rotating disc. The removed particles are extracted with the air from the chamber through the air outlet 35.

The cleaned disc is removed from the chamber by energising the solenoid 26 to withdraw the latch 25 from the slot 23 so that the disc falls between the guide plates 18 and the photocell now receives light from the lamp 27 to register the absence of a disc in the chamber 15. The photocell can be used in the control of the clean air supply to the manifold 31 and the sequence of operations in the embossing process.

We claim:

1. Apparatus for cleaning a gramophonc record disc comprising means for supporting the disc in a vertical plane for rotation about its axis, means for directing jets of gas on to the disc to cause the disc to rotate so that dust particles are removed by the combined effect of centrifugal force and the gas jets, a latch for supporting the rim of the disc, said latch being withdrawable to release the disc from the apparatus, and guide means adapted to bear against the faces of the disc,

2. Apparatus as claimed in claim 1 wherein the gas jet directing means comprises two perforated tubes adapted to lie one on either side of the disc, the perforations being directed towards the disc and in one direction of rotation.

3. Apparatus as claimed in claim 2 wherein the perforations are directed towards the part of the disc which will move upwardly as the disc rotates in the said one direction.

4. Apparatus as claimed in claim 2 wherein the perforations are of larger dimensions nearer the position of the center of the disc.

5. Apparatus for cleaning blank gramophone discs, comprising spaced vertical guide means, said guide means each defining a vertical groove and being spaced apart so that a disc is vertically slidable wit-h opposite parts of the discs rim engaging a respective groove; a withdrawable latch member having first and second positions, said latch member having a smooth surface portion which when said latch member is in said first position supports said disc in an operating position between said grooves, said latch member in said second position being Withdrawn to permit said disc to slide down said grooves from said operating position; means for moving said latch member between said first and second positions; and gas jet directing means disposed adjacent said operating position, said gas jet directing means being adapted to direct a jet of gas with a tangential component with respect to the disc onto a face of said disc, whereby said disc is rotated by said gas jet and is thereby cleaned.

6. A paratus as claimed in claim 5 further comprising a chamber defining a volume around said guide means, said gas jet directing means and said operating position, said chamber having a top wall defining an opening to permit insertion of a disc between said grooves and a bottom wall defining a further opening to permit the fall of a disc from said grooves out of the chamber; and gas extraction means for removing gas from the chamber.

7. Apparatus as claimed in claim 5 wherein said gas jet directing means comprises first and second tubes disposed to lie on either side of a disc in said operating position, each of said tubes defining perforations directed towards said disc and in a direction of rotation thereof; said tubes each being coupled to a gas supply.

References Cited UNITED STATES PATENTS 428,273 5/ 1890 Deering 274-47 X 1,525,756 2/1925 Kenney et al. 134-l39 1,914,016 6/1933 Hobi 134-138X 1,992,234 2/1935 Patterson 27447X 2,242,901 5/1941 Birch. 3,005,223 10/1961 Taylor et a1 274-47 X 3,150,401 9/1964 Taylor et al 274-47X ROBERT B. HULL, Primary Examiner. 

1. APPARATUS FOR CLEANING A GRAMOPHONE RECORD DISC COMPRISING MEANS FOR SUPPORTING THE DISC IN A VERTICAL PLANE FOR ROTATION ABOUT ITS AXIS, MEANS FOR DIRECTING JETS OF GAS ON TO THE DISC TO CAUSE THE DISC TO ROTATE SO THAT DUST PARTICLES ARE REMOVED BY THE COMBINED EFFECT OF CENTRIFUGAL FORCE AND THE GAS JETS, A LATCH FOR SUPPORTING THE RIM OF THE DISC, SAID LATCH BEING WITHDRAWABLE TO RELEASE THE DISC FROM THE APPARATUS, AND GUIDE MEANS ADAPTED TO BEAR AGAINST THE FACES OF THE DISC. 